On-chip high frequency damping for laser diode driver chips

Abstract

A laser diode driver chip is disclosed which has a circuit to substantially reduce a ringing on a laser diode driving current generated by the laser diode driver chip. This invention identifies that the ringing on the laser diode driving current is caused by three different resonances which are coupled together. This invention also suggests a model for the sources of these three different resonances and identifies the three main nodes which are common between the sources of resonances. Finally, this invention places a damping circuit between the three main nodes of the laser diode driver to substantially reduce the ringing on the laser diode driving current.

We claim: 
     
       1. A laser diode driver chip comprising: a voltage receiving node;   an output node;   a chip ground;   a first resistor;   a first capacitor;   said voltage receiving node and said chip ground being electrically connected to each other through said first resistor and said first capacitor;   said first resistor and said first capacitor between said voltage receiving node and said chip ground being in series with each other;   a second resistor;   a second capacitor;   said output node and said chip ground being electrically connected to each other through said second resistor and said second capacitor;   said second resistor and said second capacitor between said output node and said chip ground being in series with each other; and   and said laser diode driver chip, said first resistor, said first capacitor, said second resistor and said second capacitor being so constructed and arranged to substantially reduce ringing on a current generated by said laser diode driver chip.   
     
     
       2. The laser diode driver chip recited in claim 1, wherein said laser diode driver chip has a third capacitor which is electrically connected to said voltage receiving node and to said chip ground and is parallel to said first resistor and said first capacitor. 
     
     
       3. The laser diode driver chip recited in claim 1, wherein said laser diode driver chip has a fourth capacitor which is electrically connected to said voltage receiving node and to said chip ground and is parallel to said first resistor and said first capacitor. 
     
     
       4. A laser diode driver chip comprising: said laser diode driver chip having a voltage receiving node;   said laser diode driver chip having an output node;   said laser diode driver having a chip ground;   a first resistor;   a first capacitor;   said voltage receiving node and said chip ground being electrically connected to each other through said first resistor and said first capacitor;   said first resistor and said first capacitor between said voltage receiving node and said chip ground being in series with each other;   a second resistor;   a second capacitor;   said output node and said chip ground being electrically connected to each other through said second resistor and said second capacitor;   said second resistor and said second capacitor between said output node and said chip ground being in series with each other;   a third resistor;   a third capacitor;   said voltage receiving node and said output node being electrically connected to each other through said third resistor and said third capacitor;   said third resistor and said third capacitor between said voltage receiving node and said output node being in series with each other; and   said laser diode driver chip, said first resistor, said first capacitor, said second resistor, said second capacitor, said third resistor and said third capacitor being so constructed and arranged to substantially reduce ringing on a current generated by said laser diode driver chip.